1. Field of the Invention
The present invention relates generally to reading and writing data in high track density, flexible media storage applications, and more specifically, but not exclusively, to a plurality of read/write heads for reading and writing data on magnetic tape.
2. Background of the Invention
A read/write head is a device that reads and writes data from and to a magnetic tape. The surface of the tape is moved past the read/write head. The data is written using a write head. The write head contains a write coil wound around a highly permeable magnetic core consisting of write poles separated by a small gap (“write gap”). When current is passed through the coil, the movement of the current produces a magnetic field turn, magnetizes the magnetic recording media as it passes the write gap. By switching the polarity of the current in the coil, data can be stored in the media as regions of opposite magnetization polarity recorded in the magnetic recording media. The regions of recorded opposite magnetization polarity correspond to stored data bits (e.g., 1's and 0's), which are detected by a read sensor as the recorded media is passed back over the read/write head. A read/write head for high track density tape typically reads or writes multiple data channels simultaneously.
FIG. 1 depicts a pictorial representation of a conventional read/write head arrangement for a magnetic tape drive. For clarity, only a pertinent section 100 of a conventional magnetic tape drive is shown. Tape drive section 100 includes a magnetic tape 102. For example, magnetic tape 102 can be wound on a supply reel (not shown) that is rotatably mounted within a magnetic tape cartridge (not shown). Thus, magnetic tape 102 can be moved by the magnetic tape drive in a horizontal direction, as indicated by the horizontally oriented arrow in FIG. 1. As shown, magnetic tape 102 includes four groups or bands of tracks 104a-104d. However, in general, conventional magnetic tapes can also include more or less than four bands.
A typical magnetic tape (e.g., 102) consists of a Mylar substrate on which has been deposited a recording surface. The recording surface consists of a layer of magnetic material. As shown in FIG. 1, the recording surface can be subdivided into a plurality of bands (e.g., 104a-104d), each band containing a plurality of data tracks.
Tape drive section 100 also includes a movable read/write head assembly 106 positioned between tape guides (not shown). Read/write head assembly 106 includes a read/write head 108, which reads and writes data from and to magnetic tape 102. For example, a coarse and fine position actuator (not shown) moves read/write head assembly 106 in a vertical direction (as indicated by the vertically oriented arrow in FIG. 1), and positions read/write head 108 over one of the bands 104a-104d for reading and writing data from and to the magnetic media in that band (e.g., 104a) on a plurality of tracks. In order to read/write data from/to all of the bands 104a-104d, the read/write head position actuator must sequentially position the read/write head 108 over each band 104a-104d. Consequently, a major drawback of the conventional read/write head assemblies is that they require both coarse and fine positioning actuators and control for each read/write band on the magnetic tape.
In conventional magnetic tape data recording systems, the read/write data rate or data throughput can be increased in a number of ways. For example, the conventional recording systems can increase the read/write data rate by increasing the speed of the tape moving past the read/write head, the linear density of the bits stored on the tape, or the number of parallel data channels placed in the head. However, these conventional solutions are limited significantly by the magnetic and physical characteristics of the storage media being used, technical obstacles in the fabrication of conventional tape drives and heads, and limits with respect to the ingenuity of the conventional designs.
Furthermore, increasing the number of parallel data channels on a recording head places a significant demand on existing head fabrication technologies. For example, increasing the number of data channels per recording head makes the head more cumbersome because of a corresponding increase in the size and stiffness of the “flex” cable involved (cable containing conductors for carrying read bias and write currents from/to the read/write head). Also, the number of data channels per recording head is limited by the stability of the storage media used, which dictates the span and number of read/write structures that can be placed side-by-side on the head. In other words, the stability of the storage media determines just how closely spaced the magnetic (read/write) structures can be on a head and still provide acceptable yield and crosstalk values.
In this regard, by requiring more space between the magnetic read/write structures on a head, the head is required to move substantially longer distances over the storage media relative to the small width or pitch of the bands, in order to reference the entire width of the media and read or write all of the data therein. As discussed above, conventional tape drives have heads that require both coarse and fine actuators for positioning control. Thus, in order to improve data throughput in magnetic media recording systems, at a minimum, these obstacles to cost-effective head design, fabrication and the ability to increase channels, tape speed and linear bit density must be overcome.
Thus, it would be advantageous to provide an improved apparatus, system and method for reading and writing data with enhanced data throughput and positioning control in magnetic media storage applications, such as, for example, in magnetic tape drives.